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Guided Exercise: Review System Journal Entries

Search the system journal for entries to record events that match specific criteria.

Outcomes

  • Search the system journal for entries to record events based on different criteria.

As the student user on the workstation machine, use the lab command to prepare your system for this exercise.

This command prepares your environment and ensures that all required resources are available.

[student@workstation ~]$ lab start logs-systemd

Instructions

  1. From the workstation machine, open an SSH session to the servera machine as the student user.

    [student@workstation ~]$ ssh student@servera
    ...output omitted...
    [student@servera ~]$
  2. Use the journalctl command _PID=1 option to display only log events that originate from the systemd PID 1 process on the servera machine. To quit from the journalctl command, press q. The following output is an example and might differ on your system:

    [student@servera ~]$ journalctl _PID=1
    Mar 15 04:21:14 localhost systemd[1]: Finished Load Kernel Modules.
    Mar 15 04:21:14 localhost systemd[1]: Finished Setup Virtual Console.
    Mar 15 04:21:14 localhost systemd[1]: dracut ask for additional cmdline parameters was skipped because all trigger condition checks failed.
    Mar 15 04:21:14 localhost systemd[1]: Starting dracut cmdline hook...
    Mar 15 04:21:14 localhost systemd[1]: Starting Apply Kernel Variables...
    lines 1-5 q
    [student@servera ~]$
  3. Use the journalctl command _UID=81 option to display all log events that originated from a system service with a UID of 81 on the servera machine.

    [student@servera ~]$ journalctl _UID=81
    Mar 15 04:21:17 servera.lab.example.com dbus-broker-lau[727]: Ready
  4. Use the journalctl command -p warning option to display log events with a warning or higher priority on the servera machine.

    [student@servera ~]$ journalctl -p warning
    Mar 15 04:21:14 localhost kernel: wait_for_initramfs() called before rootfs_initcalls
    Mar 15 04:21:14 localhost kernel: ACPI: PRMT not present
    Mar 15 04:21:14 localhost kernel: acpi PNP0A03:00: fail to add MMCONFIG information, can't access extended PCI configuration space under this bridge.
    Mar 15 04:21:14 localhost kernel: device-mapper: core: CONFIG_IMA_DISABLE_HTABLE is disabled. Duplicate IMA measurements will not be recorded in the IMA log.
    ...output omitted...
    Mar 15 04:21:18 servera.lab.example.com NetworkManager[769]: <warn>  [1647332478.5504] device (eth0): mtu: failure to set IPv6 MTU
    Mar 15 04:21:27 servera.lab.example.com chronyd[751]: System clock wrong by -0.919695 seconds
    Mar 15 04:22:34 servera.lab.example.com chronyd[751]: System clock wrong by 0.772805 seconds
    Mar 15 05:41:11 servera.lab.example.com sshd[1104]: error: kex_exchange_identification: Connection closed by remote host
    lines 1-19/19 (END) q
    [student@servera ~]$
  5. Display all recorded log events in the past 10 minutes from the current time on the servera machine.

    [student@servera ~]$ journalctl --since "-10min"
    Mar 15 05:40:01 servera.lab.example.com anacron[1092]: Job `cron.weekly' started
    Mar 15 05:40:01 servera.lab.example.com anacron[1092]: Job `cron.weekly' terminated
    Mar 15 05:41:11 servera.lab.example.com sshd[1104]: error: kex_exchange_identification: Connection closed by remote host
    Mar 15 05:41:11 servera.lab.example.com sshd[1104]: Connection closed by 172.25.250.9 port 45370
    Mar 15 05:41:14 servera.lab.example.com sshd[1105]: Accepted publickey for student from 172.25.250.9 port 45372 ssh2: RSA SHA256:M8ikhcEDm2tQ95Z0o7ZvufqEixCFCt+wowZLNzNlBT0
    Mar 15 05:41:14 servera.lab.example.com systemd[1]: Created slice User Slice of UID 1000.
    Mar 15 05:41:14 servera.lab.example.com systemd[1]: Starting User Runtime Directory /run/user/1000...
    Mar 15 05:41:14 servera.lab.example.com systemd-logind[739]: New session 1 of user student.
    Mar 15 05:41:14 servera.lab.example.com systemd[1]: Finished User Runtime Directory /run/user/1000.
    Mar 15 05:41:14 servera.lab.example.com systemd[1]: Starting User Manager for UID 1000...
    ...output omitted...
    Mar 15 05:44:56 servera.lab.example.com systemd[1109]: Stopped target Sockets.
    Mar 15 05:44:56 servera.lab.example.com systemd[1109]: Stopped target Timers.
    Mar 15 05:44:56 servera.lab.example.com systemd[1109]: Stopped Mark boot as successful after the user session has run 2 minutes.
    Mar 15 05:44:56 servera.lab.example.com systemd[1109]: Stopped Daily Cleanup of User's Temporary Directories.
    lines 1-48 q
    [student@servera ~]$
  6. Use the journalctl command --since and _SYSTEMD_UNIT="sshd.service" options to display all the recorded log events that originated from the sshd service since 09:00:00 this morning on the servera machine.

    Note

    Online classrooms typically run on the UTC time zone. To obtain results that start at 9:00 AM in your local time zone, adjust your --since value by the amount of your offset from UTC. Alternatively, ignore the local time and use a value of 9:00 to locate journal entries that occurred since 9:00 for the servera time zone.

    [student@servera ~]$ journalctl --since 9:00:00 _SYSTEMD_UNIT="sshd.service"
    Mar 15 09:41:14 servera.lab.example.com sshd[1105]: Accepted publickey for student from 172.25.250.9 port 45372 ssh2: RSA SHA256:M8ikhcEDm2tQ95Z0o7ZvufqEixCFCt+wowZLNzNlBT0
    Mar 15 09:41:15 servera.lab.example.com sshd[1105]: pam_unix(sshd:session): session opened for user student(uid=1000) by (uid=0)
    Mar 15 09:44:56 servera.lab.example.com sshd[1156]: Accepted publickey for student from 172.25.250.9 port 45374 ssh2: RSA SHA256:M8ikhcEDm2tQ95Z0o7ZvufqEixCFCt+wowZLNzNlBT0
    Mar 15 09:44:56 servera.lab.example.com sshd[1156]: pam_unix(sshd:session): session opened for user student(uid=1000) by (uid=0)
  7. Return to the workstation system as the student user.

    [student@servera ~]$ exit
    logout
    Connection to servera closed.
    [student@workstation ~]$

Finish

On the workstation machine, change to the student user home directory and use the lab command to complete this exercise. This step is important to ensure that resources from previous exercises do not impact upcoming exercises.

[student@workstation ~]$ lab finish logs-systemd

Revision: rh199-9.3-8dd73db